A paper published this month in the prestigious medical journal The Lancet Neurologysuggests that a broad spectrum of developmental and psychiatric disorders, ranging from autism and intellectual disability to schizophrenia, should be conceptualized as different manifestations of a common underlying denominator, “developmental braindysfunction,” rather than completely independent conditions with distinct causes.
In “Developmental Brain Dysfunction: Revival and Expansion of Old Concepts Based on New Genetic Evidence,” the authors make two key points:
- Developmental disorders (such as autism and intellectual disability) and psychiatric disorders (such as schizophrenia and bipolar disorder), while considered clinically distinct, actually share many of the same underlying genetic causes. This is an example of “variable expressivity:” the same genetic variant results in different clinical signs and symptoms in different individuals.
- When quantitative measures of neuropsychological and neurobehavioral traits are studied instead of categorical diagnoses (which are either present or absent) and individuals are compared to their unaffected family members, it is possible to more accurately demonstrate the impact of genetic variants.
According to Andres Moreno De Luca, M.D., research scientist at the Autism and Developmental Medicine Institute at Geisinger Health System and article co-author, “Recent genetic studies conducted in thousands of individuals have shown that identical genetic mutations are shared among neurodevelopmental disorders that are thought to be clinically distinct. What we have seen over the past few years is that genetic mutations that were initially found in individuals with one disorder, such as intellectual disability or autism, are then identified in people with an apparently different condition like schizophrenia, epilepsy, or bipolar disorder.”
“It turns out that the genes don’t respect our diagnostic classification boundaries, but that really isn’t surprising given the overlapping symptoms and frequent co-existence of neurodevelopmental disorders,” said Scott M. Myers, M.D., autism specialist at Geisinger Health System and article co-author.
“We believe this study supports use of the term ‘developmental brain dysfunction’ or DBD, which would encompass the broad spectrum of neurodevelopmental and neuropsychiatric disorders,” said David H. Ledbetter, Ph.D., executive vice president and chief scientific officer at Geisinger Health System, and article co-author. “Additionally, it is clear that diagnostic tools such as whole genome analysis for both children and their families are essential when diagnosing and treating these disorders in order to ensure the most personalized treatment.”